Detect ZAI ZMM leaks

[SammyK]

Description

This PR adds a way to detect Zend Memory Manager leak messages in the ZAI tests by grepping the test log in CI for:

=== Total n memory leaks detected ===

There were a few ZMM leaks that were isolated to the tests (the leaks were not in the tracer or any production code paths) and those are fixed in d8b4c3e.

Ideally the leak detection would be implemented as part of the ZAI SAPI test runner, but every way I tired to implement it, I hit a blocker.

• ZMM bypasses the SAPI error logger and writes the leak message directly to stderr which I haven't been able to capture from ZAI SAPI during RSHUTDOWN.
• There is no way to inject a custom hook to capture the ZMM memory leak messages.
• I cannot get Catch2 to capture stdout or stderr from ZAI SAPI using a custom event listener; ZmmLeakListener. The event listener works, but testCaseStats.stdOut and testCaseStats.stdErr are always empty from testCaseEnded.
• Changing the Catch2 reporter to one that captures output, like junit, the custom ZmmLeakListener still cannot access ZAI SAPI stdout and stderr.
• Changing ZAI SAPI write operations from write to fwrite does not seem to make any difference.
• It seems as if the reporter doesn't even have access to the output streams; for junit, <system-out/> and <system-err/> are always empty.
• There doesn't appear to be a way to run a post-test script using cmake.

That leaves me with "manually" grepping the test log for the ZMM leak message in CI. I'm probably missing something obvious with the Catch2 setup, so if anyone else can figure out a better solution to this, I'd love to know your thoughts.

Reviewer checklist

• Appropriate labels assigned.
• Milestone is set.
• Changelog has been added to the release document. For community contributors the reviewer is in charge of this task.

[morrisonlevi]

Looks good to me!

[morrisonlevi]

I assume this was found via the added memory leak detection?

[SammyK]

It was. :)